1. Field of the Invention
The present invention relates to a semiconductor device, and particularly to a semiconductor device equipped with a penetrating electrode which is so provided as to pass through a substrate.
2. Description of Related Art
Storage capacity required for semiconductor memory devices such as DRAM (Dynamic Random Access Memory) has been growing year by year. To satisfy the requirement, in recent years, a memory device called multi-chip package has been proposed. In the multi-chip package, a plurality of memory chips are stacked. However, in the case of the multi-chip package, a wire needs to be provided for each chip to connect each memory chip and a package substrate. Therefore, it is difficult to stack many memory chips.
On the other hand, in recent years, a semiconductor device of a type in which a plurality of memory chips with penetrating electrodes are stacked has been proposed (See Japanese Patent Application Laid-Open No. 2005-136187). In the semiconductor device of the type, among penetrating electrodes provided on each memory chip, the penetrating electrodes that are provided on the same plane position when seen from a stacking direction are electrically short-circuited. Therefore, even if the number of chips stacked increases, the number of electrodes connected to the package substrate does not increase. Thus, it is possible to stack a larger number of memory chips.
When semiconductor chips with penetrating electrodes are stacked, bump electrodes that are provided on upper and lower chips need to be in accurate contact with each other. Accordingly, compared with an operation of stacking chips in the multi-chip package, more accurate positioning is required. As for a device used to stack semiconductor chips having penetrating electrodes, the device disclosed in Japanese Patent Application Laid-Open No. 2006-49417 is known.
However, when the semiconductor chips are stacked, even as accurate positioning is carried out, the bonding strength between the semiconductor chips could be uneven if the semiconductor chips are warped. In such a case, there is the possibility that the bump electrodes, which should be originally bonded together, come off from each other, possibly lowering the reliability of products.